This invention relates to switched communications networks. More particularly, this invention relates to a switched communications network in which certain types of call traffic are redirected to avoid the network switch, thereby freeing up switch resources.
One example of a known switched communications network is the public switched telephone network. In that network, individual subscriber lines are connected to a local switching office, which houses a large switch, capable of connecting one subscriber line to another subscriber line or to a trunk line that connects to other switching offices. Each incoming or outgoing line occupies one termination at the local switching office. However, the number of "ports" in the switch--i.e., the number of lines that can be in use at any one time--is smaller than the number of terminations, based on statistical "call blocking" objectives that rely on the fact that not all subscriber lines will be in use at all times, and on the acceptability of the unavailability of a port to a subscriber for a small percentage of the time if the number of lines in use exceeds the number of ports.
Known "call blocking" models are based, inter alia, on certain assumptions regarding the volume and duration of calls. As the product of volume and duration increases, so does the number of ports. The number of ports provided in switches heretofore has been determined based on traditional voice calling patterns.
With the increasing popularity, however, of on-line services such as the Internet, the existing assumption have begun to break down because of the increasing volume of voice-band data calls, which tend to have much longer durations than traditional voice calls. As a result, the number of ports provided in existing switches may soon, if not already, be inadequate. Heretofore, the only remedy for this situation has been the provision of more switch resources, either by providing additional switches, or larger switches. Because of the great expense of telephone switches, that option may not always be practical.
It would be desirable to be able to provide a method for handling increased volumes of calls on a switched communications network using existing switch capacity or with a slower increase in the required switch capacity.